Currently, common communication modules include third-Generation (3G) modules and fourth-Generation (4G) modules, which mainly use Universal Serial Bus (USB) interfaces (specifically, Mini-PCIe (Peripheral Component Interconnect Express) interfaces), and are plugged into terminals, such as mobile phones and tablet computers, and connected to host systems in the terminals, thereby implementing an Internet connecting function. A hot plugging operation is usually performed when the 3G/4G module is used in a USB interface of the terminal. In other words, a user is allowed to remove or replace the 3G/4G module without shutting down the system or powering off the associated terminal. In this manner, the 3G/4G module can be removed by simple plugging and unplugging actions, and the system continues to run normally without interruption, thereby, improving disaster recovery capability, extensibility and flexibility of the system.
However, existing 3G/4G modules have the following problems during hot plugging:
1. USB interface data is damaged. During design of a Printed Circuit Board (PCB) of a conventional 3G/4G module, all signal pins and data pins have a same length. For example, a USB data pin D+ (Data+, positive data), a USB data pin D− (Data−, negative data) and a power source pin of a USB data interface have the same length. When the 3G/4G module is removed, communication and data of the USB are disconnected at the same time, and at this time, transmission of data may not be completed, and there is not enough time for the host system to store the data, thereby, causing loss of at least a part of the data.
2. A large transient current is generated at a power source interface. When the 3G/4G module is plugged in, a power source voltage output by the host system is immediately input to a power source end of the 3G/4G module, thereby, generating a large transient current. The large transient current may burn out elements in a power source module of the 3G/4G module, causing working disorders and even breakdown of the system.
3. A large transient current is generated when the 3G/4G module is started immediately after being connected to a power source. After the conventional 3G/4G module is plugged in, the host system starts the module immediately. Because the 3G/4G module is started immediately after being powered on, a large transient current is generated, which causes a transient drop in a power source voltage of the host system, thereby, severely affecting stability and reliability of the system.
Therefore, the prior art needs to be modified and improved.